Shell and tube evaporator



Aug. 20, 1935. w. H. CARRIER 2,012,133

SHELL AND TUBE EVAPQRATOR Filed March 9; 1934 2 Sheets-Sheet 1 000 000000 0000 0000 coco- 000 0000 0000 000 000 I2 0000 0000 0000 000 0000 0000000 000 oooooooooooooooooo 27 ooooooooooooooooo 7 ooooooooooooooooooOOOOOOOOOOOOOOOOO INVENTOR I M11110 1-! Corner ATTORNEY 1935. I w. H.CARRIER 2,

I SHELL AND TUBE EVAPQRATOR 1 Filed larch 9, 1934* 2 Sheets-Sheet 2 inJ3 1% s x E INVENTOR.

Zdzlhs-H Carrzer ATTORNEY Patented Aug. 20, 1935 PATENT OFFICE SHELL ANDTUBE EVAPORATOR Willis 11. Carrier, Elizabeth, N. 1., assignor to aCarrier Engineering Corporation, Newark, N. 1.,

a corporation of New York I Application March 9,

7 Claims.

vide a shell and tube evaporator, the shell of which may readily beconstructed of welded steel and which will be smaller in size andgenerally less expensive than comparable present day evaporators. Tothis end, this invention may be combined with that of my copendingapplication, Serial No. 714,768 filed March 9, 1934.

Another object of the invention is to provide an evaporator in which therefrigerant charge is considerably less than the refrigerant charge ofpresent day evaporators of the same type and equal refrigeratingcapacity.

Still another object of the invention is to utilize the evaporator forstoring the liquid refrigerant during periods when the evaporator isinoperative; and to prevent freezing of the lower tubes of theevaporator during the periods when the refrigerant is stored therein.

A further object of the invention is to prevent the accumulation of anysubstantial quantity of liquid refrigerant within the base of theevaporator shell during the periods when the evaporator is operative.

A feature of the invention resides in the provision in a shell and tubeevaporator of a collecting pan beneath the tube net for directingtowards a central outlet any refrigerant liquid which falls thereon.

In connection with the foregoing feature, another feature of theinvention resides in providing an outlet in the pan which permits freeand smooth fiow from the pan into the outlet from the shell.

A further feature of the invention resides in forming atrough in thecollecting pan, which trough has a maximum width and depth proximate thecentral outlet and a minimum width and depth at a point farthest fromthe outlet; and in so forming the edges of the pan that every portionthereof has a definite slope towards the central outlet.

Still another feature of the invention resides in mounting thecollecting pan within the base of the shell in such a manner that thespace beneath the pan may be used for refrigerant storage purposes.

The above objects and features, and various others making for efliciencyand economy, will be more apparent from the following description to beread in connection with the accompanying drawings, in which:

1934, Serial No. 714,767

Fig. 1 is an elevation, partly in section, showing the evaporatorgenerally, and the positioning of the pan within the base of the shell;

Fig. 2 is a plan view of the para;

Fig. 3 is an elevation of the pan; and

Figs. 4 and 5 are sections (.f infinitesimal length taken on the lines4-4 and 5-5, respectively,of Fig. 3.

With reference to the drawings, similar designations referring tosimilar parts, numeral Ill designates a cylindrical' shell having one ormore vapor outlets H proximate the top thereof. The outlets H, andscroll l2, provide communication between the shell and any desiredpoint, for example, the inlet of a centrifugal compressor (not shown). Aplurality of tubes l3, constituting a nest, or bundle, pass through theshell Ill and are held, at the opposite ends thereof in suitable tubesheets. Water, or any other medium to be cooled, is admitted to thetubes, and withdrawn therefrom, through suitable water boxes attached tothe ends of shell l0.

Liquid refrigerant, from a refrigerant condenser, for example, isadmitted to the shell l0 through supply pipe l9. Pump 20, illustrateddiagrammatically, withdraws liquid from the base of shell l0, throughoutlet 2|, and pipe 22; and discharges this liquid through one or morerefrigerant distributing headers 23, positioned above the tube nest. Therefrigerant is discharged from the headers in a plurality of streams,and upon striking the tubes is subdivided by impact into very fineparticles, as illustrated. In this manner, a very complete distributionof liquid over the entire top of the tube nest is secured. The liquidflows by gravity from the first row of tubes, to the second, to thethird, etc., thus covering each tube with a thin film of refrigerant.Any excess falls from the lowest row of tubes and is collected forrecirculation by the pump 20. Refrigeration is, of course, secured inthe usual manner by evaporating a portion of the refrigerant from thetube surfaces, the resulting vapor being. removed from the shell throughthe outlets II and the scroll 12.

In order tomaintain the desired circulation of liquidover the tubes, itis necessary to maintain a head of liquid in the stand pipe 22. With theusual cylindrical evaporator, this would entail maintaining a head ofseveral inches of liquid in the base of the shell, in order that therefrigerant may flow towards the outlet 2|. In other words, in such anevaporator, a quantity of liquid which has no function in therefrigerating process must be supplied. Since the refrigerant isexpensive and for other obvious reasons, this useless excess should bekept to a minimum. -Applicant accomplishes this by providing a pan 24beneath the tube nest. The pan is substantially constant in widththroughout its length, but is so constructed that every part thereof isinclined toward an opening 25, which opening is directly above theoutlet 2| in the base of the shell. As can be seen in the drawings, atrough 26 is formed along the longitudinal center line of the pan, whichtrough widens and deepens from a minimum at each end to a maximum at theopening 25. Conversely (Fig. 2) the upturned edges 21 have a maximumwidth and minimum slope towards the longitudinal center line at the endsthereof and a minimum width and maximum slope at a point opposite theoutlet 25. Further (Fig. 3), the edges 21 slope from the ends thereoftoward theopening 25. With this arrangement, it is evident that anyliquid dropping from the tubes l3, or discharged into the shell throughthe inlet pipe I9, is immediately directed towards the opening 25,hence, the outlet 2!, and stand pipe 22; and that the flow does notdepend upon the maintenance of a head of liquid in the base of theshell.

Whenever the refrigerating machine is shut down, substantially theentire refrigerating charge collects at one point. Further, whenever there frigerating load is very light, the pump 20 will be stopped, andhence, the liquid in the pump and circulating system, and therefrigerant returned from the condenser through pipe l9 will drain intothe evaporator. While various expedients might be used, applicantprefers to store the liquid in the base of the evaporator shell.However, if all the liquid were collected in the pan 24, then the tubenest would have to be raised above the position shown in the drawings toprevent covering the lower tubes l3 and thus endangering freezing theliquid therein; and if the tube est is raised, then a shell larger thanthe shell illustrated must be used. Applicant avoids these possibilitiesby mounting the pan in such a way that the refrigerant may collectbeneath the pan in the spaces 28, as well as in the pan itself. In otherwords, the liquid falling on the pan is directed towards the centraloutlet 25, flows into and fills up the stand pipe 22, and then theliquid backs up through openings 30 (between pan 24 and shell l0) andfills the spaces beneath the pan to the same level as the liquid in thepan. If necessary, holes 29 may be provided at one or more points alongthe upper part of edges 21 for the purpose of venting the spaces 29. Ascan be.

Hence, substantially the en-' may be used and is considered to be withinthe purview 01' this invention.

Since certain changes in carrying out the above process and in theconstructions set forth, which embody the invention, may be made withoutdeparting from its scope, it is intended that all matter contained inthe above description or shown 'in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

I claim:

1. In an evaporator, a shell, a tube nest passing through said shell, aliquid outlet from said shell, means for discharging liquid from thebase of said shell over said tube nest, and a pan beneath said tube nestfor collecting the liquid falling therefrom and directing said liquidtoward said liquid outlet.

2. In an evaporator, a shell, a tube nest passing through the shell, aliquid outlet from the shell, and a pan beneath said tube nest, said panhaving an opening therein located above the outlet from the shell, saidpan being formed to direct liquid falling thereon toward said opening,said pan being so mounted in the base of said shell as to provide liquidstorage space therebeneath.

3. In an evaporator, a shell, a tube nest passing through the shell, aliquid outlet from the base of the shell, means for discharging liquidover the tube nest, and a collecting pan beneath said tube nest, saidpan having a liquid outlet therein smaller than and located above theoutlet from the shell, said pan being so mounted in the shell as' toprovide liquid storage space therebeneath.

4. In an evaporator, a shell, a tube nest passing through the shell,means for discharging liquid over said tube nest, a liquid outlet in thebase of said shell, and a pan beneath said tube nest, said pan having anopening therefrom located above the outletfrom the shell, said pan beingso formed that every part thereof slops toward said opening.

5. In an evaporator, a slash, a tube nest passing through the shell,means for admitting liquid into said shell, a liquid outlet from saidshell, and a pan located beneath said tube nest for directing liquidtowards said outlet by gravity, said pan being so mounted in said shellas to provide liquid storage space therebeneath.

6. In an evaporator, a shell, a tube nest passing through said shell,means for admitting liquid into said shell, a liquid outlet from saidshell, a pan beneath said tube nest for directing liquid falling thereontowards the outlet from said shell, said pan being so mounted in saidshell as to provide liquid storage space therebeneath, and means forventing said liquid storage space.

'7. In an evaporator, a cylindrical shell, a liquid outlet from the baseof said shell, a tube nest passing through said shell, ,means fordischarging liquid over said tube nest, and a pan in the base of saidshell beneath said tube nest, said pan having a trough formed thereinfor directing liquid towards said liquid outlet, the edges of said panbeing upturned for directing liquid into said

